NEW YORK − Police arrested two North African-born men in a sting operation after they bought a hand grenade and guns to attack a New York City synagogue, authorities said yesterday. Algerian-born Ahmed Ferhani, 26, and Moroccan-born Mohammed Mamdouh, 20, bought three pistols, ammunition and an inert grenade after a seven-month sting operation, according to police and Manhattan prosecutors.

The plot unraveled on Wednesday and would constitute the 13th planned attack by Islamist militants on New York City since the September 11, 2001, attacks. New York has remained a target for Al-Qaida and police went on heightened alert following the May 2 killing of Osama Bin Laden by U.S. special forces.

In a separate case two years ago, four men were arrested for placing what they thought were explosives outside synagogues in New York City’s Bronx borough. The men, who were caught in an FBI sting operation, were videotaped making vitriolic anti-Semitic statements to an FBI informant. They were convicted following a trial in Manhattan federal court and await sentencing.

Following yesterday’s arrests, the Jewish Federations of North America said in a statement that the reports of a home-grown terror plot were disturbing.